RU2741046C1 - Method for production of large-size contour annular article from heat-resistant nickel-base alloy - Google Patents

Abstract

FIELD: metal forming.

SUBSTANCE: invention relates to metal forming and can be used in production of large-size contour annular articles from heat-resistant nickel-based alloys, in particular, a turbine housing. A circular billet is obtained by depositing and subsequent piercing of a vacuum arc remelting ingot with diameter of 500 mm. Rectangular ring is produced from annular billet by hot drawing in 3-5 cycles. Each cycle includes methodical heating and rolling. After the first cycle, the workpiece is annealed. Then, hot forming is followed by shaping the workpiece and heat treatment.

EFFECT: as a result, higher efficiency of articles manufacturing and improvement of their structure and mechanical properties.

1 cl, 1 dwg, 1 tbl

Description

1. Field of technology

The invention relates to the processing of metals by pressure, and in particular to methods for manufacturing large-sized complex-contour annular products made of heat-resistant nickel-based alloys, in particular, the turbine housing. The proposed method includes obtaining an annular billet by upsetting and subsequent piercing of an ingot of vacuum arc remelting with a diameter of 500 mm, hot rolling of the original annular billet to obtain a ring of rectangular section. Hot rolling of the initial circular blank is carried out in 3-5 cycles, each of which includes methodical heating and rolling, and after the first cycle of hot rolling the blank is annealed. Then, after hot stamping, the billet is profiled and heat treated. EFFECT: method makes it possible to obtain large-sized complex-contour annular products made of heat-resistant nickel-based alloy and provides maximum productivity and economy of the process.

2. Prior art

The known "Method for the manufacture of solid-rolled rings from heat-resistant nickel alloys" (Patent RU 2 349 410 (B21H 1/06, C22F 1/10), 2007) includes the manufacture of a forged ring blank, its heating, hot rolling in conditions close to isothermal, and subsequent heat treatment of the ring obtained as a result of rolling. The disadvantage of this method is that the technical solution does not provide for the production of complex contour rings.

Known "Method for the manufacture of rolled ring blanks from high-alloy nickel alloys" (Patent RU No. 2335372 (B21H 1/06, C22F 1/10), 2007), including upsetting, piercing, punching and distillation in diameter, then the rolled blank is heat treated in the overaging mode and calibrated for diameter in a heated state. The disadvantage of this method is the impossibility of its use for the manufacture of large-sized products and the impossibility of providing a full guarantee of prevention of cracking.

Known "Method of manufacturing rolled circular blanks from high-alloyed nickel alloys" (Patent RU No. 2342215 (B21H 1/06, B21K 21/02, B21J 5/00, B21J 1/06), 2006), including obtaining an initial circular blank of rectangular section, hot rolling, calibration and heat treatment of the rolled blank. The disadvantage of this method is the high labor costs for the manufacture of large-sized products.

It is also known, adopted by the applicant for the closest analogue, "A method of manufacturing a large-sized annular part of a gas turbine engine from a heat-resistant alloy on a nickel basis" (Patent RU 2703764 (B21K 21/08, B21N 1/06, 2019) including hot stamping of a solid-rolled billet obtained by upsetting of a vacuum arc ingot weighing about two and a half tons, subsequent piercing, broaching and rolling of the pierced billet, and subsequent thermal and mechanical treatment of the profiled billet.

The disadvantage of the prototype method is that the technical solution does not stipulate the heating mode for rolling the workpiece and does not provide for the production of complex contour products.

3. The essence of the invention

3.1. Technical problem statement

The objective of the present invention is to obtain a large-sized complex-contoured product from a heat-resistant alloy on a nickel basis, to ensure maximum productivity and economy of the process.

The result of solving a technical problem

The solution to the problem is achieved by hot stamping of a circular billet of rectangular cross-section, followed by profile rolling and heat treatment. A billet of rectangular cross-section is obtained by upsetting a vacuum arc ingot with a diameter of 500 mm and a weight of about two and a half tons, followed by piercing of the upset billet, hot rolling and mechanical processing. This achieves: high productivity, reduced labor intensity, improved structure and mechanical properties of finished products.

3.2. Features

In contrast to the known technical solution, which includes obtaining an initial circular billet of rectangular section, obtaining a profiled billet from it and heat treatment; in the claimed technical solution, the initial circular billet of rectangular cross-section, obtained by upsetting and subsequent piercing of a vacuum arc ingot with a diameter of 500 mm, is hot rolled for 3 ÷ 5 cycles, while the metal is heated methodically, and after the first cycle, annealing is carried out, after which hot stamping, profile rolling and heat treatment.

Hot rolling is carried out using a smooth roll and mandrel to obtain a solid-rolled rectangular ring. The rolling is carried out in 3 ÷ 5 continuously repeating cycles. The cycles include heating and rolling operations.

Heating for rolling is carried out according to the mode: the temperature of the furnace when planting the metal should not be higher than 400 ° C, then hold at this temperature for at least 2 hours, after which the temperature is increased to 600 ÷ 650 ° C at an arbitrary speed and the exposure is not performed. less than 1 hour, then the temperature is raised to 1170 ÷ 1190 ° C at a rate of no more than 70 deg / hour and holding at this temperature is carried out for at least 1 hour.

After completing the first rolling cycle, annealing is performed to relieve internal stresses and eliminate the formation of cracks during subsequent machining and deformation. Annealing is performed according to the following regime: heating at a temperature of 1050 ÷ 1080 ° C, holding at this temperature for 2 ÷ 3 hours, cooling with a furnace to a temperature of no more than 600 ° C and then in air.

The solid-rolled rectangular ring obtained after rolling is subjected to intermediate machining and hot stamping is performed. Stamping of a solid-rolled rectangular-section ring includes extrusion of a symmetrical workpiece by a driven punch in the volume formed by the surfaces of the upper and lower tools.

Then, profile rolling is carried out in a compound caliber using a prefabricated mandrel-mandrel. In this case, heating for profile rolling is carried out according to the mode: the temperature of the furnace when planting the metal should not be higher than 400 ° C, then hold at this temperature for at least 2 hours, after which the temperature is increased to 600 ÷ 650 ° C at an arbitrary speed and hold for at least 1 hour, then raise the temperature to 1170 ÷ 1190 ° C at a rate of no more than 70 deg / hour and hold at this temperature for at least 1 hour.

After rolling, the complex-contour annular product is subjected to heat treatment, which is carried out according to the following mode:

- quenching with a temperature of 1130 ÷ 1150 ° C, exposure 1.0 ÷ 1.5 hours, air cooling;

- aging 780 ÷ 830 ° C, exposure 15 hours, air cooling.

Further, the final machining of the complex contour product is carried out.

3.3. List of drawing figures

FIG. 1 shows a block diagram of a method for manufacturing large-sized complex-contour ring products from a heat-resistant alloy on a nickel base, where 1. - Preparation of an ingot of vacuum arc remelting, 2. - Upsetting and piercing of a dimensional billet on a press 200MN, 3. - Hot rolling on a ring rolling mill , 4. - Intermediate machining, 5 - Stamping on a press 200MN, 6. - Profile rolling, 7. - Heat and final machining.

4. Description of the invention

In the claimed technical solution, the possibility of manufacturing a large-sized complex-contour annular product from a solid billet obtained by hot stamping with subsequent profiled rolling is considered. The general production scheme is as follows:

Vacuum arc remelting ingot 0500 mm (~ 2500 kg) → mechanical processing of the ingot and cutting to length → upsetting + piercing, press 200MN → rolling on a ring rolling mill (KPS) → mechanical processing → stamping, press 200MN → profile rolling → thermal and final mechanical restoration.

An ingot of vacuum arc remelting 0500 mm (weighing ~ 2500 kg) is subjected to machining (up to 15 mm per side) and cut to the measured length. Then I make bevels 30 × 45 ° on both sides (Fig. 1, block 1).

To form a fine-grained structure and obtain the required level of mechanical properties, as well as to exclude the formation of rough surface defects during deformation, the metal is heated methodically, excluding a sharp temperature difference between the surface and inner layers according to the mode: the furnace temperature during metal planting should not be higher than 400 ° С, then hold at this temperature for at least 2 hours, after which the temperature is increased to 600 ÷ 650 ° C at an arbitrary speed and hold for at least 1 hour, then the temperature is raised to 1170 ÷ 1190 ° С at a speed no more than 60 deg / hour and hold at this temperature for 3 ÷ 4 hours.

The upsetting of the heated measuring workpiece is carried out to a height of 510 mm, after which, in two strokes, the upset workpiece is pierced by piercing in a ratio of 1 to 3 of the piercing diameter to the diameter of the upset workpiece, using graphite and sawdust as a lubricant. From the beginning, preliminary piercing is performed to a depth of 1/3 of the height of the workpiece, then the workpiece is turned 180 ° and the final piercing is performed (Fig. 1, block 2).

Then, hot rolling is carried out using a smooth roll and a mandrel to obtain a solid-rolled rectangular ring. The rolling is carried out in 3 ÷ 5 continuously repeating cycles. The cycles include the operation of heating and rolling the billet (Fig. 1, block 3).

Heating for rolling is carried out according to the mode: the temperature of the furnace when planting the metal should not be higher than 400 ° C, then hold at this temperature for at least 2 hours, after which the temperature is increased to 600 ÷ 650 ° C at an arbitrary speed and the exposure is not performed. less than 1 hour, then the temperature is raised to 1170 ÷ 1190 ° C at a rate of no more than 70 deg / h and holding at this temperature is carried out for at least 1 hour.

After completing the first rolling cycle, annealing is performed to relieve internal stresses and eliminate the formation of cracks during subsequent machining and deformation. Annealing is performed according to the following regime: heating at a temperature of 1050 ÷ 1080 ° C, holding at this temperature for 2 ÷ 3 hours, cooling with a furnace to a temperature of no more than 600 ° C and then in air.

The solid-rolled rectangular ring obtained after rolling is subjected to intermediate machining and stamping (Fig. 1, block 4 and 5). The punching of the ring includes the extrusion of a symmetrical workpiece by a driven punch in the volume formed by the surfaces of the upper and lower tools. Before heating for deformation, a suspension prepared from bustilate and refractory cement is applied to the entire surface of the solid-rolled ring. During the transportation of the rings, the manipulator jaws, in the zone of contact with the metal, are insulated with mullite-silica material. Before stamping, a lubricant consisting of graphite and water is applied to the working surface of the tool.

Then carry out the profile rolling in a compound caliber using a prefabricated mandrel-mandrel (Fig. 1, block 6).

Heating for profile rolling is carried out according to the following mode: the furnace temperature during metal planting should not be higher than 400 ° C, then hold at this temperature for at least 2 hours, after which the temperature is increased to 600 ÷ 650 ° C at an arbitrary speed and hold not less than 1 hour, then the temperature is raised to 1170 ÷ 1190 ° C at a rate of no more than 70 deg / h and holding at this temperature is carried out for at least 1 hour.

After rolling, the complex-contour annular product is subjected to heat treatment (Fig. 1, block 7), which is carried out according to the following mode:

- quenching with a temperature of 1130 ÷ 1150 ° C, exposure 1.0 ÷ 1.5 hours, air cooling;

- aging 780 ÷ 830 ° C, exposure 15 hours, air cooling.

Further, the final machining of the complex contour product is carried out (Fig. 1, block 7).

As a result of using the proposed method, the quality of the solid-rolled rings of rectangular cross-section obtained after rolling increases due to the provision of the optimal hole piercing and the elimination of cracking during rolling.

The use of the proposed method makes it possible to obtain large-sized complex-contour annular products from a heat-resistant alloy on a nickel base and to achieve high productivity, reduce labor intensity, improve the structure and mechanical properties of finished products.

5. An example of a specific implementation (implementation of the method)

The implementation of the method is shown on the example of EP708-VD alloy. The product was manufactured according to the following scheme:

Vacuum arc remelting ingot ∅500 mm (~ 2500 kg) → machining of the ingot and cutting to length → upsetting + piercing, press 200MN → rolling on a ring rolling mill (KPS) → mechanical processing → stamping, press 200MN → profile rolling → thermal and final machining.

A vacuum arc ingot with a diameter of 500 mm was machined and cut to length. Then upsetting was carried out and the upsetting workpiece was pierced in two strokes. From the beginning, preliminary piercing was carried out to a depth of 1/3 of the height of the workpiece, then the workpiece was turned 180 ° and the final piercing was performed.

Next, the circular billet was hot rolled on a ring rolling mill to obtain a solid-rolled rectangular ring. The rolling was carried out in 4 continuously repeating cycles, including the operations of heating and rolling the billet. In this case, after completing the first rolling cycle, annealing was performed according to the following regime: heating at a temperature of 1050 ÷ 1080 ° C, holding at this temperature for 2 ÷ 3 hours, cooling with a furnace to a temperature of no more than 600 ° C and then in air.

The solid-rolled rectangular ring obtained after rolling was subjected to intermediate machining and stamping. After that, profiled rolling was carried out in a composite caliber using a prefabricated mandrel-mandrel and the product was subjected to heat treatment. Heat treatment was carried out according to the following regime: quenching with a temperature of 1130 ÷ 1150 ° C, holding 1.0 ÷ 1.5 hours, cooling in air, then aging at 780 ÷ 830 ° C, holding for 15 hours, cooling in air.

Then completed the final machining of the complex-contour annular product.

The resulting product belongs to the first control group according to OST 100021, which provides for the control of mechanical properties and macrostructure at the annular allowance of each ring.

The quality control of the product was carried out in the amount of OST 1 90396 on samples cut from the annular allowance in the state of delivery. The level of mechanical properties at a temperature of 20 ° C on specimens cut in the tangential direction meets the requirements of OST 1 90396 and has a sufficient margin for all characteristics. The macrostructure is satisfactory. The results of the control tests are presented in table 1.

The use of the above method makes it possible to obtain large-sized complex ring products made of EP708-VD heat-resistant nickel alloy, which fully comply with the mechanical properties and macrostructure requirements of OST 1 90396 “Solid-rolled precision rings made of alloyed corrosion-resistant, heat-resistant and heat-resistant steels and alloys. General technical conditions ".

Claims (2)

1. A method of manufacturing a large-sized complex-contour annular product from a heat-resistant alloy on a nickel base, including obtaining an initial annular billet by upsetting and subsequent piercing of an ingot of vacuum arc remelting with a diameter of 500 mm, hot rolling of an initial annular billet to obtain a ring of rectangular cross-section, subsequent hot stamping and heat treatment characterized in that the hot rolling of the initial annular workpiece is carried out in 3-5 cycles, each of which includes methodical heating and rolling, after the first cycle of hot rolling, the workpiece is annealed, and after hot stamping, the profile rolling of the heated workpiece and heat treatment are performed, while methodical heating of the workpiece before rolling and its heating before profile rolling is carried out in a furnace, the temperature of which when planting the workpiece is not higher than 400 °, the workpiece is held at the specified temperature for at least two hours, then those the temperature in the furnace up to 600-650 ° С at an arbitrary speed and held for at least one hour, after which the temperature is raised to 1170-1190 ° С at a rate of no more than 70 degrees / hour and the holding at this temperature is carried out for at least one hour, annealing the workpiece includes its heating in a furnace at a temperature of 1050-1080 ° C, holding at this temperature for 2-3 hours, cooling with a furnace to a temperature of no more than 600 ° C and then in air, and heat treatment is carried out by quenching at a temperature of 1130- 1150 ° C, exposure 1.0-1.5 hours, cooling in air, subsequent aging at a temperature of 780-830 ° C with exposure for 15 hours and cooling in air. 2. The method according to claim 1, characterized in that before hot stamping, the rectangular ring is subjected to intermediate machining.

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